Characterization of the magnetic modification of Co/Pt multilayer films by He+, Ar+, and Ga+ ion irradiation

Abstract

Co/Pt multilayers can exhibit large perpendicular anisotropies and coercivities that are very sensitive to the quality of the Co/Pt interfaces. We have characterized the dependence of coercivity of Co/Pt multilayers on irradiation with various ion species (He+, Ar+, and Ga+), energies (20 keV–2 MeV), and doses (1011–1017 ions/cm2), in order to understand better the nature of the structural changes responsible for the magnetic changes. We find that, in general, the system is much more sensitive to irradiation than expected on the basis of a nearest-neighbor coupling model and simple ballistic ion-beam mixing.

Ga+ion irradiation-induced changes in magnetic anisotropy of a Pt/Co/Pt thin film studied by X-ray magnetic circular dichroism

“…Among them, the control of magnetic anisotropy by ion irradiation has attracted much interest in this decade [1][2][3][4][5][6][7][8][9], due to a possibility of nanostructure patterning by using a focused ion beam [3,5]. In fact, a Ga + -induced spin reorientation transition to perpendicular magnetization from an inplane magnetized Pt/Co/Pt thin film has been reported at medium ion fluences in the 10 14 ions/cm 2 region [1].…”

Study of focused-ion-beam–induced structural and compositional modifications in nanoscale bilayer systems by combined grazing incidence x ray reflectivity and fluorescence

“…18,19 The pioneering work of Chappert et al 20 on the Co=Pt magnetic systems stimulated numerous studies focused on the influence of the ion irradiation and implantation on the perpendicular magnetic anisotropy (PMA) systems. [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36] In-plane magnetic systems, such as Permalloy (nominal composition Ni 80 Fe 20 ), have also attracted interest, and some similar studies have been conducted on those systems. [37][38][39] Energy transfer from the incident ions can cause atomic displacements of target atoms, leading to intermixing across the interface.…”

Arrays of magnetic nanoindentations with perpendicular anisotropy

“…1 In conventional lithography a pattern is typically created in a resist layer which is subsequently transferred to a magnetic film. The pattern generation can be accomplished with a number of technologies such as electron beam lithography, 2,3 ion beam lithography, [4][5][6][7][8] near field lithography, 9,10 laser interference lithography, [11][12][13][14] x-ray lithography, 15,16 or nanoimprint. 17,18 Unfortunately, most methods may not be suitable for largescale device fabrication because they are multistep, expensive, and involve time-consuming procedures.…”